Is your statement still valid about using comp. level above 5 will kill "seek" function, if so, whats the main reason? libflac version used on the box? Dont they update the libflac every release?
I did some tests.
The production of a fully functioning FLAC file, should start from a clean source: a WAV file,
rather than extraction from the CD and compression in one action "on the fly".
That's the important thing to get a FLAC file fully seekable with all the necessary metadata.
Compression levels greater than "5" are not directly responsible for the loss of "seek" function
although they are not convenient in terms of [processing speed] / [file size],
since the algorithm is optimized to the default value which is "5".